A secondary battery (e.g., a non-aqueous electrolyte lithium secondary battery) and a capacitor are provided with tab leads for extracting electricity to the outside. In a secondary battery, one end of a tab lead is connected to a battery element and clamped by and between opposing outer casing films, and the other end thereof is extended to the outside of the outer casing films. The seal portion of the tab lead which is to be clamped by and between the outer casing films is desired to have excellent adhesiveness by heat sealing.
The outer film is provided with a metal layer, such as, e.g., an aluminum foil, as an intermediate layer. Therefore, in order to prevent short-circuit of the metal layer and the tab lead (metal), an insulating resin film is integrally interposed between the tab lead and the outer casing film.
For example, in anon-aqueous electrolyte battery structured such that a positive electrode, a negative electrode and electrolyte are accommodated in a sealed bag made of a laminated film including a metal foil and that lead wires connected to the electrodes are extended to the outside, it is known to provide an insulating layer which does not melt at the heat sealing temperature of the sealed bag so as to cover the extending portion of the lead wire and an insulating layer which melts at the heat sealing temperature of the sealed bag arranged outside of the insulating layer which does not melt at the heat sealing temperature (see Patent Document 1).
Further, in a battery, it is also known to provide a laminated film including a metal layer and a heat adhesive resin layer containing a heat adhesive resin, a battery element covered by the laminated film, a lead connected to the battery element, clamped by and between the opposing heat adhesive resin layers, and extended to the outside of the laminated film, and a film-like sealant (insulating film) arranged between the lead and the heat adhesive resin layer and including a heat adhesive resin and fine resin fibers mixed with the heat adhesive resin (see Patent Document 2).    Patent Document 1: Japanese Patent No. 3505905    Patent Document 2: Japanese Unexamined Laid-open Patent Application Publication No. 2011-249343